Lactose intolerance occurs when an individual has a deficiency in lactase, an enzyme the human body produces to help break down lactose from foods. Lactose is a sugar found in milk and other dairy products such as cheeses and yogurt. Lactose intolerance should not be confused with a milk protein allergy, a condition involving the immune system that can cause severe allergic reactions after consuming proteins found in milk according to the Mayo Foundation for Medical Education and Research. Some people with lactose intolerance are able to tolerate soy milk and certain dairy products.
Background
People who are lactose intolerant experience unpleasant side effects after consuming lactose-containing milk or milk products. Unpleasant side effects such as diarrhea, gas, abdominal bloating, pain or nausea may occur 1/2 to 2 hours after consuming lactose according to the National Digestive Diseases Information Clearinghouse. Unlike people with a cow's milk allergy who may also have an allergy to soy milk proteins, people who are lactose intolerant are typically able to tolerate soy milk.
Soy Milk
Soy milk is made with soy protein, a plant-based food source and is a common alternative to cow's milk for people who are lactose intolerant or vegetarians. Soy is one of the few plant proteins that is a complete protein, meaning it contains all essential amino acids the human body cannot manufacture itself. Soy milk is typically fortified with nutrients such as calcium.
Soy vs. Cow's Milk
Cow's milk contains about 8 grams of protein per serving, is high in calcium and typically fortified with vitamins A and D. Similarly soy milks such as plain Silk, provide about 7 grams of protein per serving according to the U.S. Department of Agriculture Nutrient Data Laboratory. Many types of soy milk are also fortified with vitamins A, D, calcium, omega 3 fatty acids and other beneficial nutrients.
Concerns
Although light varieties of soy milk are available, many brands of soy milk are higher in fat than 1 percent or skim cow's milks. One cup of skim milk is fat free, while the same serving of Silk original soy milk contains about 4 grams of total fat, equivalent to over one-third of total calories coming from fat according to the U.S. Department of Agriculture Nutrient Data Laboratory. The fats found in soy milk are mainly heart-healthy mono- and polyunsaturated fats, however.
Recommendations
When following a 2,000 calorie diet, the U.S. Department of Agriculture recommends consuming 3 cups of milk or other dairy products per day to maintain a healthy eating plan. Since soy milk is similar in composition to cow's milk, the two can be interchangeable in a meal plan especially when consuming lower-fat varieties of soy milk. People with lactose intolerance can often tolerate low-lactose dairy products such as hard cheeses or yogurt. Lactose-free milks are also available; so are lactase tablets that can be consumed with lactose-containing products to reduce unpleasant symptoms of lactose intolerance.
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